feat: use ZKP as submitOrder argument

[marcuspang]

For some reason, there was an error when I tried to run some tests

chain:test:     Argument 1 of method DarkPool.submitOrder is not a provable type: function Function() { [native code] }
chain:test: 
chain:test:       70 |     Runtime: config,
chain:test:       71 |   });
chain:test:     > 72 |   await appChain.start();